Tue, January 23, 2024 Turnagain Pass Avalanche Forecast

Tue, January 23rd, 2024

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

1 - Low

Wed, January 24th, 2024

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

1 - Low

Wed, January 24th, 2024

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

1 - Low

0 - No Rating

1 - Low

2 - Moderate

3 - Considerable

4 - High

5 - Extreme


Travel Advice	Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.	Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.	Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.	Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.	Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches	Natural and human-triggered avalanches unlikely.	Natural avalanches unlikely; human-triggered avalanches possible.	Natural avalanches possible; human-triggered avalanches likely.	Natural avalanches likely; human-triggered avalanches very likely.	Natural and human-triggered avalanches certain.
Avalanche Size and Distribution	Small avalanches in isolated areas or extreme terrain.	Small avalanches in specific areas; or large avalanches in isolated areas.	Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.	Large avalanches in many areas; or very large avalanches in specific areas.	Very large avalanches in many areas.

Recent Avalanches

No new avalanches were reported yesterday. However, there are so many brown streaks from glide avalanches that it’s getting hard to tell what ones are new and what are old. Thank you to all the folks for writing in with photos and comments of new and old glide cracks and avalanches. Being able to compare these photos is our best tool at deciphering the timing.

Avalanche Problem 1

Glide Avalanches
N E S W NW NE SE SW

Aspect/Elevation
Certain

Very Likely

Likely

Possible

Unlikely

Likelihood
Historic (D4-5)

Very Large (D3)

Large (D2)

Small (D1)

Size

Glide Avalanches

Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.

Aspect/Elevation of the Avalanche Problem

Specialists develop a graphic representation of the potential distribution of a particular avalanche problem across the topography. This aspect/elevation rose is used to indicate where the particular avalanche problem is thought to exist on all elevation aspects. Areas where the avalanche problem is thought to exist are colored grey, and it is less likely to be encountered in areas colored white.

Likelihood of Avalanches

Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches

Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

Signal Word	Size (D scale)	Simple Descriptor
Small	1	Unlikely to bury a person
Large	2	Can bury a person
Very Large	3	Can destroy a house
Historic	4 & 5	Can destroy part or all of a village

More info at Avalanche.org

Today is the 16th day since the last snow storm at Turnagain Pass and one of the coldest mornings yet in valley bottoms (-23F at the Granite Ck weather station near Johnson Pass trailhead). For the last week, the mountains have been under mostly clear skies, light winds, and very cold to even warm temperatures in the high terrain. Snow surfaces are variable, everything from thin surface crusts, wind effect, and soft settled power exist. But clearly, many of us are anticipating a return stormy weather, maybe early next week.

In the meantime, we are in a LOW danger regime for human triggered avalanches. That means triggering an avalanche is unlikely, but not impossible. Examples would be stepping onto a cornice and causing it to break off, finding an unstable wind slab in steep rocky terrain, and creating sluffs on steep slopes with loose surface snow.

The wild card is being in the wrong place at the wrong time when a glide avalanche releases. With these full-depth destructive avalanches occurring every now and then in high traffic areas, the danger is at MODERATE. It’s critical to watch for glide cracks and avoid being near or under them as much as possible. If you do find yourself in a threatening location or choose to travel under these, be sure to watch the slope, go one at a time, and move fast.

Glide cracks that were noticed near the up-route on Lipps Ridge at Turnagain Pass on Sunday. They can look just like crevasses at times. Photo Ayla Crosby, 1.21.23.

Glide cracks pointed out on the west face of Cornbiscuit. None of these have released yet on this face, but could at any time. Photo Trevor Clayton, 1.21.23.

Weather

Tue, January 23rd, 2024

Yesterday: Mostly sunny skies were over the region yesterday with light and variable winds. Temperatures were downright cold, -10 to +10F at all elevations.

Today: Another mostly sunny and cold day is expected. Ridgetop winds should remain light from a north or west direction. Temperatures should be between -10 to +15F at all elevations. The coldest air is found in valley bottoms, yet the higher elevations are not nearly as warm as they were last week.

Tomorrow: The high pressure over Southcentral is looking to stick around into the weekend. Hence, clear and cold weather should persist Wednesday into Saturday. Models are hinting at a chance for stormy weather to return Sunday or Monday. Cross your fingers!

PRECIPITATION 24-hour data (6am – 6am)

	Temp Avg (F)	Snow (in)	Snow Depth (in)
Center Ridge (1880′)	-3	0	77
Summit Lake (1400′)	-9	0	n/a
Alyeska Mid (1700′)	0	9	75
Bear Valley – Portage (132′)	-4	0	–
Grouse Ck – Seward (700′)	6	0	51

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	9	var	4	10
Seattle Ridge (2400′)	5	N	2	10

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
05/13/24	Turnagain	Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South	H Thamm
05/13/24	Turnagain	Observation: Turnagain Pass non-motorized side	Amy Holman
05/12/24	Turnagain	Observation: Warm up Bowl	Tony Naciuk
05/07/24	Turnagain	Observation: Turnagain Pass Wet Slabs	A S
04/29/24	Turnagain	Avalanche: Turnagain aerial obs	Tully Hamer
04/27/24	Turnagain	Observation: Johnson Pass	Noah Mery
04/23/24	Turnagain	Observation: Turnagain Sunny Side	Travis SMITH
04/21/24	Turnagain	Observation: Bertha Creek	Anonymous
04/20/24	Turnagain	Avalanche: Spokane Creek	Schauer/ Mailly Forecaster
04/16/24	Turnagain	Observation: Cornbiscuit	Krueger / Matthys Forecaster

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